The temporal magnetic resonance (MR) appearance of human brain tissue during formalin fixation was measured and modeled using a diffusion mathematical model of formalin fixation. Coronal MR images of three human brains before formalin fixation and at multiple time points thereafter were acquired. T₁ relaxation, T₂ relaxation, water apparent diffusion coefficient (ADC), and proton density (PD) maps were calculated. The size of a light “formalin band” region, visible in T₁ weighted images, was compared to a mathematical model of diffusive mass transfer of formalin into the brain. T₁ relaxation, T₂ relaxation, and PD all decreased, in both gray and white matter, as formalin fixation progressed. The ADC remained more or less constant. The location of the inner boundary of the formalin band followed a time course consistent with the steepest formalin concentration gradient in the mathematical model. Based on the diffusion model, the brain is not completely saturated in formalin until after 14.8 weeks of formalin immersion and, based on the observed changes in T₁, T₂, and PD, fixation is not complete until after 5.4 weeks. During fixation, the ongoing attenuation of T₁ relaxation, T₂ relaxation, and PD must be taken into consideration when performing postmortem MRI studies. Magn Reson Med 54:324–332, 2005.

The Kepler satellite reveals details of the oscillations patterns of an evolved star in an exotic triple-star system.

Trength trained the free arm (CAST-TRAIN). The second group (n = 7) wore a cast and did not strength train (CAST). Casts were applied to the nondominant (left) wrist and hand. Strength training was maximal isometric handgrip contractions (right hand) 5 d·wk−1. Peak force (handgrip dynamometer), muscle thickness (ultrasound), EMG, and cortical activation (functional magnetic resonance imaging) were assessed before and after the intervention. Results: CAST-TRAIN improved right handgrip strength by 10.7% (P < 0.01) with no change in muscle thickness. There was a significant group × time interaction for strength of the immobilized arm (P < 0.05). Handgrip strength of the immobilized arm of CAST-TRAIN was maintained, whereas the immobilized arm of CAST significantly decreased by 11% (P < 0.05). Muscle thickness of the immobilized arm decreased by an average of 3.3% (P < 0.05) for all participants and was not different between groups after adjusting for baseline differences. There was a significant group × time interaction for EMG activation (P < 0.05), where CAST-TRAIN showed an increasing trend and CAST showed a decreasing trend, pooled across arms. For the immobilized arm of CAST-TRAIN, there was a significant increase in contralateral motor cortex activation after training (P < 0.05). For the immobilized arm of CAST, there was no change in motor cortex activation. Conclusions: Handgrip strength training of the free limb attenuated strength loss during unilateral immobilization. The maintenance of strength in the immobilized limb via the cross-education effect may be associated with increased motor cortex activation....